Midory outdated

looks like Midory that comes with Trisquel 8 is already outdated. What is the point of releasing it in that case? Can't login to LinkedIn. Browser is too old. As far as I need the working system not just privacy concerns I do switch back to XUbuntu.

6 years old is not that old. My old laptop was a budget laptop from 2007 and it worked with MATE, Cinnamon, GNOME, etc just fine. Pretty much any x86 computer from 2012 should easily be able to handle any modern desktop environment, even KDE. In fact the newest hardware that can work with a 100% libre software stack (that is to say, the Libreboot-supported computers) are older than that.

Loading speed is influenced almost entirely by how fast your hard drive is. How many seconds are you talking about with regard to loading speed? If it's more than a few seconds or so I would seriously consider replacing that hard drive since such slow operation could be an early sign that it's developing too many bad sectors. Using a lightweight DE that loads less stuff is only a band-aid solution and isn't going to protect you from the inevitable data loss.

On the other hand, if it's only a few seconds that's bothering you, that's because you're using a hard drive, not because of the age of your computer. You can get faster read/write speeds with an SSD.

Also, Xfce is available on Trisquel; just install the "xfce4" meta-package.

By running Trisquel mini you are never prevented to install QupZilla hence abandon discontinued Midori at your own will and own need. Trisquel is free software so you are always free to install anything that meets freedom.

Epiphany is a great browser that’s written for GNOME, for systems that don’t have Falkon/QupZilla like PureOS and Hyperbola I run Epiphany as the only browser for these systems, however for Trisquel there is QupZilla so I run QupZilla as my default web browser.
Note that package your-privacy in Parabola blocks geoclue2 that also blocks WebKitGTK+ so finally blocks Epiphany, but I still have QupZilla that’s secured to keep using it. :)

Parabola ships QupZilla version 1.8.9 that uses QtWebKit engine,https://parabola.nu/packages/QupZilla1
An KDE browser using QtWebEngine that now merges QupZilla and Konqueror, called Falkon, is also available in Parabola, but the QtWebEngine deps are virtual packages to be ignored.
Parabola should also try to liberate QtWebEgine by removing ‘‘Pepper’’ Flash plugins and deps then publish in their [nonprism] repo,https://parabola.nu/packages/falkon
Parabola also ships WebKit2GTK in [nonprism] repo that doesn’t need geoclue2,https://parabola.nu/packages/webkit2gtk

The browser is called Qupzilla, but the rendering engine qt5-webengine was replaced (as opposed to modified by removing non-free parts) by qt5-webkit so it is in fact a different browser using the same name.

For light-weight browser, QupZilla is recommended (and also by gnu.org).

For light-weight desktop environment, why do I feel that MATE is even lighter than Xfce... One fact is that Xubuntu is beginning to use certain MATE components.

PS, I am running Trisquel on a twelve years old notebook. It has an Atheros WLAN adapter and no ME. I learned that the initial generation ME for 945 platforms is located in the Intel Gib ethernet adapter. But my LAN adapter is non-Intel, so I'm not troubled by ME. Everything is so perfect under Trisquel.

There's also a Cinnamon desktop similar to MATE which both are GNOME forks, as compared to LXQt or MATE is Cinnamon really light? I have some nostalgia reason using Cinnamon from which I was still running nonfree Linux Mint, that's the system developing Cinnamon desktop.

Is LXQt ugly mainly depends on kwin, xfwm, or openbox as win manager, and what are your control and icon themes. (Yes kwin and xfwm are quite pretty but Openbox is honestly ugly.) :)
For me I just love Breeze-dark control, mouse, icon themes from KDE for LXQt and sometimes GTK desktops like Cinnamon and MATE, which I also have installed Openbox/KDE for experimenting is that more light than standard Plasma shell.
In parallel I've also installed Ubuntu touch, Chrome OS, winxp, win10 themes that looks very different from GNOME's Adwaita.
For Parabola you will have one more choice, https://liri.io, for Trisquel you will also have Unity shell as one more choice. :D